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Biomedical subjects

C D Morgan

Publications and source records attributed to C D Morgan.

At least 55 records · Page 3Linked to original sources
PubMed1995

Definitive landmarks for reproducible tibial tunnel placement in anterior cruciate ligament reconstruction.

The purpose of this prospective study was to define constant anatomic intraarticular and extraarticular landmarks that can be used as definitive reference points to reproducibly create a tibial tunnel for anterior cruciate ligament (ACL) reconstruction that (1) results in an impingement-free graft in full extension without an intercondylar roofplasty; (2) positions the tibial tunnel's intraarticular orafice sagittally central in the original ACL insertion without visually guessing; (3) positions the tibial tunnel such that the sagittal tunnel-plateau angle is parallel with the sagittal intercondylar roof-plateau angle in full extension to minimize shear seen by the graft at the tibial tunnel inlet, and by doing so; (4) maximizes tunnel length to avoid patellar tendon graft-tunnel length mismatch allowing for endosteal interference screw fixation on both sides of the joint. Anatomic dissections in 50 knees showed the ACL sagittal central insertion point on the intercondylar floor averages 7 mm (range 7 to 8 mm) sagittally anterior to the anterior margin of the posterior cruciate ligament (PCL) with the knee flexed 90 degrees such that the PCL may be used as a reliable reference landmark for locating the ACL sagittal central insertion. This constant relationship was found to be independent of knee size. Extraarticularly, beginning the tibial tunnel sagittally 1 cm above the superior (sartorial) border of the pes anserinus insertion and coronally 1.5 cm posteromedial from the medial margin of the tibial tubercle along the superior surface of the pes, directed toward the sagittal central ACL insertion, led to a sagittal tunnel-plateau angle that averaged 68 degrees (range 64 degrees to 72 degrees) with a corresponding tunnel length that averaged 58 mm (range 50 to 65 mm) in 23 knees. This data correlated well with data obtained clinically in a series of 50 consecutive ACL reconstructions using intraarticular PCL and extraarticular pes anserine-medial tibial tubercle referenced tibial tunnels in which postoperative full extension lateral radiographs confirmed a sagittal tunnel-plateau angle parallel or near parallel with the intercondylar roof-plateau angle in all cases averaging 68 degrees +/- 3.8 degrees. Tibial tunnel length averaged 60 mm (range 52 to 66 mm) and in no case was there a patellar tendon autograft-tunnel length mismatch.

Anterior Cruciate Ligament↗
PubMed1995

Isometry testing for anterior cruciate ligament reconstruction revisited.

The purpose of this study was to determine the effect, if any, that varying the distal testing position (tibial level) has on isometry data produced with a common anatomic proximal testing position at the native anterior cruciate ligament (ACL) origin. During ACL reconstruction in 25 knees, in vivo isometry measurements were recorded using two different isometry testing methods, which differed in the tibial level of the distal fixation testing point. Method 1 tested distally at a point 13 cm peripheral to the native ACL insertion on a vector in line with the tibial tunnel. Method 2 tested distally at a point central in the native ACL insertion at the level of the intercondylar floor. All tibial tunnels were standardized with similar sagittal tunnel-plateau angles and similar tunnel lengths. The proximal testing point was standardized at a point that was anatomically located at or near the central ACL origin 7 mm anterior to "over the top" in all knees. Using these methods, length changes between the proximal and distal testing points were recorded in each knee with each testing method, with the knee ranged from 70 degrees of flexion to full extension and from 70 degrees to 140 degrees of flexion. From these data, a total excursion from 0 degree to 140 degrees of flexion was calculated. A nonanatomic distal testing point (Method 1) produced a 6 mm +/- 1 mm total excursion, whereas anatomic testing points (Method 2) in the same knees produced a 1 mm +/- 1 mm total excursion. From these data, the authors conclude that the tibial level of the distal isometry testing point has a significant effect on the resultant isometry measurement such that anatomic testing points are most isometric. Isometers that produce data between nonanatomic testing points should not be used to position tunnels for ACL reconstruction and should not be used to assume the elongation forces an ACL substitute will see when fixed at different points. Conversely, the clinical relevance of this study is that both anatomic graft position and anatomic graft fixation position are important and, when achieved, should result in minimal graft elongation with early postoperative range of motion, leading to a more stable long-term result.

Anterior Cruciate Ligament↗
PubMed1995

Sexual functioning and attitudes of eating-disordered women: a follow-up study.

The sexual experiences and attitudes of eating disorder patients are receiving increased professional attention. However, empirical work in this area has generally focused on these patients at the point of initial evaluation. In the current study we report the results of a follow-up questionnaire completed by women who had been treated in our clinic (N = 42) for either anorexia nervosa (restricting type) or bulimia nervosa (purging type). We found that former anorectic patients were less likely to return the questionnaire and, of those who did, there was a trend toward anorectic women's being less likely to be in a romantic/erotic relationship. Almost all of the women had engaged in sexual intercourse, and former anorectic patients did not differ from bulimics with regard to age at first coitus. Anorectics were less likely than bulimics to have engaged in masturbation and also scored lower on a measure of sexual esteem. Although there were no differences between the two groups with regard to current level of sexual functioning, erotophobia/erotophilia, or sexual satisfaction, the women in our sample exhibited less sexual interest and more negative affect during sex than did a normative sample. Also, nearly 40% of our sample indicated clinically significant levels of sexual discord with their current partner. Results are discussed with regard to prior research, interventions, and further study.

Adolescent↗
PubMed1995

Odor identification as an early marker for Alzheimer's disease: impact of lexical functioning and detection sensitivity.

The impact of lexical functioning and detection sensitivity on the deficit of odor identification in Alzheimer's disease (AD) was studied in persons diagnosed with probable and questionable AD. Tests consisted of lexical-based odor identification, lexical-based picture identification, picture-based odor identification, and odor-detection threshold. Results suggest (1) that odor identification is poorer than picture identification in probable and questionable AD, (2) that odor identification continues to be poor even when lexical demands are eliminated, (3) that odor detection does contribute to the odor-identification deficit, but does not account for it completely, and (4) that odor identification tests have a correct classification rate of 83-100%. Odor identification tests can be very useful tools in diagnosing AD and should be considered an important addition to existing diagnostic test batteries.

Aged↗
PubMed1995

Probable immune system mediation of the antitumor activity of the 2,6-dimethoxybenzo-p-semiquinone radical.

We recently reported that the antitumor activity of an immobilized oxidase-peroxidase system, which can produce radical species as intermediates, is dependent on the presence of an intact and functioning immune system in the host. A number of recent investigations have indicated that the bioactive form of many quinone-type anticancer agents may be the semiquinone-type radical. To investigate if the antitumor activity of some of the quinone-type anticancer agents may also be dependent on a fully functioning immune system in the host, we used as a simple, well-defined model the 2,6-dimethoxybenzo-p-semiquinone radical. This free radical has a potent antitumor activity against Ehrlich ascites tumors in mice, as first described by Szent-Gyorgyi's group. In the present study, we investigated its antitumor activity in immunocompromised BALB/c mice. We found that the antitumor activity of the semiquinone radical is completely abolished in mice that had previously been subjected to whole body gamma irradiation, indicating a possible involvement of one or more cells of the host's defense system. The antitumor activity was not abolished in mice with dysfunctional macrophages induced by a severe selenium deficiency. However, the radical was inactive in mice whose immune system was suppressed with cyclosporin A and in nude (nu/nu) mice. These results suggest that the dimethoxybenzo-semiquinone radical, rather than acting primarily as a cytotoxic agent as previously reported, exerts its antitumor activity mainly via a more complex mechanism in which T lymphocytes appear to play a major role.

Animals↗
PubMed1995

Recent developments in reperfusion therapy for acute myocardial infarction.

The efficacy, and mechanisms of benefit, of thrombolytic therapy in reducing mortality following myocardial infarction are time-dependent. Early treatment results in myocardial salvage and preservation of left ventricular function, mediated through prompt restoration of normal antegrade infarct artery perfusion. Later treatment exerts favourable effects on electrical stability of the myocardium and may attenuate progressive left ventricular dilation independent of myocardial salvage. Tissue plasminogen activator, administered using an accelerated, front loaded dosing regimen, affords early infarct artery patency which is superior to that achieved with streptokinase and is associated with a small, but significant, further reduction in mortality. The implications for choice of thrombolytic agent in a cost-contained health care system are examined, as is the importance of minimizing in-hospital delay in administering thrombolytic agents in the setting of acute myocardial infarction (AMI). Recognition of the pivotal role of patency and the shortcomings of thrombolytic agents in achieving optimal reperfusion has lead to renewed interest in percutaneous transluminal coronary angioplasty (PTCA) as primary therapy for AMI, Preliminary results are promising but must be confirmed in larger studies. Primary PTCA should be considered for patients with AMI and contraindications to thrombolytic therapy.

Angioplasty, Balloon, Coronary↗
PubMed1994

Handedness and hemispheric differences for feature perturbations.

The influence of handedness on hemispheric differences for feature perturbations was assessed in left- and right-handed normal subjects, with equal numbers of each sex in each group. Stimulus displays consisting of five small squares arranged in a single row were presented tachistoscopically to the left or right of fixation, and the size of the squares was manipulated in different conditions. Subjects were instructed to state in which square a horizontal "tick" mark was located. The handedness of the subjects contributed to the pattern of hemispheric differences for tick mislocations resulting from feature perturbations in the toward-fovea direction. For left-handed subjects, fewer errors occurred when stimuli were presented to the left hemisphere; for right-handed subjects, fewer errors occurred when stimuli were presented to the right hemisphere. Increasing stimulus size tended to enhance the handedness and hemispheric feature perturbation effects. The data suggest that handedness contributes to hemispheric organization of featural extraction processes.

Adult↗
PubMed1994

Effects of thrombolytic therapy administered 6 to 24 hours after myocardial infarction on the signal-averaged ECG. Results of a multicenter randomized trial. LATE Ancillary Study Investigators. Late Assessment of Thrombolytic Efficacy.

BACKGROUND: Thrombolytic therapy reduces mortality after acute myocardial infarction, even when treatment is initiated relatively late after onset of symptoms. The mechanism underlying this survival benefit is incompletely understood. METHODS AND RESULTS: In a prospectively designed ancillary study of a randomized, placebo-controlled trial of late thrombolytic therapy (LATE), the signal-averaged (SA) ECG was recorded before hospital discharge in an effort to assess the effect of thrombolytic therapy on arrhythmia substrate. Three hundred ten patients were enrolled at 23 participating sites; 160 patients received placebo, and 150 patients received recombinant tissue-type plasminogen activator (rTPA) therapy 6 to 24 hours after onset of symptoms. Compared with placebo, rTPA tended to reduce the frequency of SAECG abnormality (filtered QRS duration > 120 milliseconds) by 37% (95% CI, -64%, +6%; P = .087) and the filtered QRS duration (105.7 +/- 13.8 versus 108.8 +/- 14.6 milliseconds, P = .05). In the prespecified subgroup of 185 patients with ST elevation on the qualifying ECG, rTPA resulted in a 52% reduction (95% CI, 4% to 77%, P = .011) of SAECG abnormality and a shorter filtered QRS duration (105.7 +/- 10.9 versus 110.7 +/- 15.9 milliseconds, P = .01). No benefit was seen in patients without ST elevation on ECG. CONCLUSIONS: Late thrombolytic therapy produced a more stable electrical substrate, which probably represents an important mechanism of mortality benefit.

Double-Blind Method↗
PubMed1994

5-Fluorouracil related toxic myocarditis: case reports and pathological confirmation.

This report describes two cases of cardiotoxicity associated with the use of 5-fluorouracil (5-FU) in the treatment of neoplastic disease, and reviews the literature to date. The manifestations of cardiac toxicity were significant ventricular dysfunction during continuous infusion of 5-FU, accompanied by symptoms resembling cardiac ischemia in one case and irreversible cardiogenic shock in another. Detailed cardiac investigations and pathological findings provide convincing evidence that the development of acute myocarditis is the likely mechanism of 5-FU cardiotoxicity, rather than coronary insufficiency as has commonly been postulated. Although cardiotoxicity as a complication of 5-FU therapy remains rare, recognition of this entity is important as it may lead to serious hemodynamic compromise and may recur with drug rechallenge.

Acute Disease↗
PubMed1994

Graded exercise testing following thrombolytic therapy for acute myocardial infarction: the importance of timing and infarct location. TPAT Study Group.

OBJECTIVES: To determine the influence of timing, infarct location and thrombolytic therapy on the electrocardiographic (ECG) response to exercise testing following acute myocardial infarction. DESIGN: Maximal treadmill exercise testing was performed on postinfarction day 8 and repeated on day 90 as part of a previously reported double-blind, placebo controlled study of recombinant tissue plasminogen activator (rt-PA) in acute myocardial infarction in which left ventricular function was the primary end-point. Patients were systematically evaluated for left ventricular function, myocardial perfusion and coronary anatomy. SETTING: Ten collaborating community and academic hospitals. PATIENTS: One hundred and fifteen patients, aged 20 to 75 years, with ischemic chest pain 30 mins or longer and ST elevation on ECG. Patients with cardiogenic shock, left bundle branch block, prior aortocoronary bypass surgery, recent percutaneous transluminal coronary angioplasty or standard contraindications to thrombolytic therapy were excluded. MAIN RESULTS: The analysis is confined to the 70 patients who underwent both exercise tests without intercurrent coronary revascularization. Peak rate-pressure product was greater on day 90 than on day 8 (mean difference +/- SE 2.2 +/- 0.6 x 10(3), P = 0.001), whereas 65% of patients had 1 mm or greater of exercise-induced ST shift on day 8 compared with 47% on day 90 (P = 0.025). Patients following anterior compared with inferior infarction were more likely to have exercise-induced ST elevation (54% versus 21%, P = 0.012) but less likely to have ST depression (29% versus 63%, P = 0.017) on day 8; results were directionally similar on day 90. Treatment with rt-PA, compared with placebo, did not influence exercise performance, the ECG response to exercise or the extent of inducible ischemia on thallium scintigraphy. CONCLUSIONS: Timing and infarct location are important modifiers of the ECG response to exercise testing following myocardial infarction. Thrombolytic therapy in these uncomplicated patients did not influence inducible ischemia.

Adult↗
PubMed1993

Are routine non-invasive tests useful in prediction of outcome after myocardial infarction in elderly people?

Many patients with acute myocardial infarction undergo tests to identify ischaemia, left-ventricular dysfunction, and arrhythmias. We examined the usefulness of these tests in clinical practice by comparing the ability of a cardiologist to predict outcome at 1 year after infarction with and without knowledge of the results of an exercise test, radionuclide angiogram, and 24 h Holter electrocardiographic (ECG) recording. The study was limited to patients older than 65 years, who have a greater risk of cardiovascular sequelae and undergo fewer interventional procedures. The patient's own cardiologist predicted outcome on a standard rating scale, based on clinical findings and routine hospital tests. He then made a second prediction after seeing the non-invasive test results. Two other cardiologists not involved in the care of the patient independently made similar predictions. Success in predicting outcome was assessed by comparison of differences between the first and second predictions in the area under receiver operating characteristic curves. During 1 year's follow-up there were 24 cardiovascular deaths and 3 recurrent myocardial infarctions among the 147 patients. There were no significant differences in mean curve areas between the first and second predictions for the patients' own cardiologist (0.62 [SE 0.06] vs 0.60 [0.06]) or the other cardiologists (0.63 [0.06] vs 0.64 [0.06] and 0.61 [0.06] vs 0.65 [0.06]). All predictions were significantly (p < 0.05) better than chance. Prediction of outcome in older patients after myocardial infarction is not improved by knowledge of the results of an exercise test, radionuclide angiogram, or 24 h Holter ECG recording.

Aged↗
PubMed1993

Waiting for coronary revascularization in Toronto: 2 years' experience with a regional referral office.

OBJECTIVES: To determine the frequency of major adverse events among patients awaiting coronary revascularization; to assess the match between referring physicians' estimates of urgency, a computer-generated multifactorial urgency rating score and actual waiting times; to determine the changes in waiting times as capacity for bypass surgery increased; and to evaluate the influence of choice of procedure or operator on waiting times. DESIGN: Consecutive case series. SETTING: Greater Toronto region. SUBJECTS: All 571 patients referred to an organized referral office by cardiologists at hospitals without on-site revascularization facilities between Jan. 3, 1989, and June 30, 1991. MAIN OUTCOME MEASURES: Preoperative fatal or nonfatal myocardial infarction; proportions of patients waiting longer than the maximum period recommended for their urgency rating; mean waiting times for various subgroups; and correlations among referring physicians' urgency ratings, computer-generated multifactorial urgency scores and waiting times. RESULTS: Of the 496 patients accepted for a procedure 5 had fatal cardiac events and 3 nonfatal myocardial infarction. Events occurred three times more often in patients with left mainstem disease than in those in other anatomic categories (relative risk [RR] 3.05, 95% confidence interval [CI] 1.48 to 6.27, p = 0.03). Both the computer-generated scores and the referring physicians' scores were correlated with the actual waiting time (r = 0.46 and 0.57 respectively). Waiting times and the proportion of patients with excessive waiting times fell during the study period (p < 0.0001). However, urgent cases were much less likely to be done "on time" than those with a recommended waiting time of more than 2 weeks (RR 0.16, 95% CI 0.11 to 0.25, p < 0.0001). The mean wait for coronary artery bypass grafting (CABG) was 22.73 days if the referral office was allowed to find a surgeon or interventional cardiologist and 35.31 days if one was requested (p = 0.002 after adjustment for urgency scores). CONCLUSIONS: Death of a patient on the waiting list is uncommon in an organized referral system. Patients with left main-stem disease are at higher risk of death than those in other anatomic categories. There were significant correlations between referring physicians' ratings of urgency, multifactorial urgency scores and actual waiting times. Expansion of capacity for CABG led to shorter waiting times, but patients with unstable symptoms continued to wait longer than recommended. Requests for a specific surgeon caused significantly longer delays.

Aged↗
PubMed1993

Impact of tissue plasminogen activator and heparin versus heparin alone on quantitative coronary angiographic findings in myocardial infarction. The Toronto Tissue Plasminogen Activator Trial Study Group.

The influence of tissue plasminogen activator (t-PA) and heparin versus heparin alone on anatomic characteristics of patent infarct-related coronary arteries and the development of these angiographic descriptors in coronary arteries that remain patent during the hospital course was examined in 108 patients who participated in a placebo-controlled trial of recombinant tissue-type plasminogen activator in acute myocardial infarction. Coronary angiography was performed 18 +/- 6 hours after treatment in 47 patients (group A) and at 10 days in 61 patients (group B). Quantitative coronary angiography of the infarct-related lesion was performed, and luminal irregularity was quantitated with an ulceration index. Of the 47 patients in group A, 7 (29%) treated with placebo had Thrombolysis in Myocardial Infarction grade 2 or 3 perfusion, whereas 18 (78%) treated with t-PA had grade 2 or 3 (p < 0.001); there was no difference between patients who had grade 2 or 3 perfusion in group B (placebo 59% vs t-PA 75%). In group A, at 10 days, the luminal area of the infarct artery had increased from 0.59 +/- 0.11 to 0.9 +/- 0.24 mm2 and from 0.75 +/- 0.16 to 1.31 +/- 0.39 mm2 for placebo- and t-PA-treated patients, respectively (p < 0.04). There was no change in the ulcerative index over time in either placebo- or t-PA-treated patients. It is concluded that early after infarction, t-PA produces marked and rapid improvement in overall patency as compared with heparin, although this difference was attenuated at 10 days because of spontaneous recanalization in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Antitumor activity of an immobilized peroxidase system against murine Ehrlich ascites is mediated by the immune system.

Earlier studies have shown that a mixture of glucose oxidase and a peroxidase exerts a tumoricidal effect on rats bearing Novikoff hepatomas when the enzyme mixture is injected intraperitoneally. The enzyme mixture was shown to be nontoxic when injected into healthy animals at levels up to 600 times the therapeutic dose. In the present study, we have evaluated the possibility that the host immune defense system may be involved in the antitumor activity of the peroxidase system, using the murine Ehrlich ascites tumor as the target. The results revealed that the antitumor activity of the peroxidase system is absent in tumor-bearing animals whose immune system has been compromised by whole body gamma-irradiation or by an induced selenium deficiency. The peroxidase system was also found to be inactive in tumor-bearing mice whose immune system was suppressed by the administration of cyclosporin A as well as in athymic (nu/nu) mice. These results indicate that T lymphocytes may directly or indirectly be involved in the in vivo antitumor activity of the peroxidase system. This could explain the observed high selectivity toward tumor cells by the enzyme system in vivo and its lack of toxicity in healthy animals.

Animals↗
PubMed1992

Pathophysiology and prognostic significance of Holter-detected ST segment depression after myocardial infarction. The Tissue Plasminogen Activator: Toronto (TPAT) Study Group.

OBJECTIVES: We performed Holter monitoring on days 4 and 7 after acute myocardial infarction in 109 patients to assess whether ST segment shift would identify those with more severe coronary artery disease, left ventricular dysfunction and unfavorable prognosis. BACKGROUND: Silent myocardial ischemia is a frequent and prognostically significant event after acute myocardial infarction. However, the specific pathophysiologic mechanisms and the impact of thrombolytic therapy are uncertain. METHODS: In addition to Holter monitoring, patients underwent exercise testing, radionuclide angiography on days 1 and 9 and quantitative coronary angiography on day 9. RESULTS: Thirty-five patients (32%) had ST segment depression and had similar recombinant tissue-type plasminogen activator (rt-PA) treatment assignment and a reduced cross-sectional area of the infarct-related artery (0.59 +/- 0.57 vs. 1.04 +/- 1.26 mm2, p < 0.05). Global left ventricular function improved from day 1 to day 9 in patients without (4% +/- 11%, p < 0.001) but not in those with (0% +/- 7%) ST segment depression. In-hospital event rates were similar; however, follow-up 18 +/- 11 months after hospital discharge revealed a greater frequency of death and recurrent myocardial infarction in patients with compared with those without ST segment depression (27% vs. 6%, p = 0.03). CONCLUSIONS: After acute myocardial infarction, approximately one third of patients have ST segment depression on Holter monitoring, independent of the use of thrombolytic therapy. The unfavorable prognosis observed in these patients may be related to greater lumen obstruction in the infarct-related artery and lack of improvement in left ventricular function.

Cardiac Catheterization↗
PubMed1992

Unexplained elevated maternal serum alpha-fetoprotein is not predictive of adverse perinatal outcome in an indigent urban population.

OBJECTIVE: The null hypothesis of this study is that in an urban, indigent obstetric population at high risk for adverse perinatal outcome, unexplained elevations of maternal serum alpha-fetoprotein are not an additional predictor of adverse perinatal outcome. STUDY DESIGN: Perinatal outcomes of 72 patients from a clinic for indigent patients with unexplained elevated maternal serum alpha-fetoprotein levels were compared with those of matched controls from the same population with normal maternal serum alpha-fetoprotein levels. Subjects and controls were matched for age, race, parity, and presence or absence of Hollister risk factors. The frequency of adverse perinatal outcome in the two groups was subjected to matched-pair chi 2 analysis. RESULTS: Adverse perinatal outcome occurred in 38.9% (28 of 72) of subjects with unexplained elevated maternal serum alpha-fetoprotein levels greater than or equal to 2.5 multiples of the median, compared with 31.9% (23 of 72) of controls with normal maternal serum alpha-fetoprotein levels (p = 0.5). No statistically significant difference in adverse perinatal outcomes was found. CONCLUSIONS: Elevated maternal serum alpha-fetoprotein levels offer little if any additional predictive value for adverse perinatal outcome in populations already at high risk for such outcomes on the basis of obstetric or socioeconomic criteria.

Adolescent↗
PubMed1992

Arthroscopic-assisted glenohumeral arthrodesis.

A case of successful glenohumeral arthrodesis performed under arthroscopic control is presented. Clinical and radiographic fusion occurred by 6 weeks after the procedure. Salient features of the procedure include arthroscopic debridement of all hyaline cartilage and subchondral bone on both sides of the joint, reduction in a functional position, and internal fixation with percutaneously placed screws.

Adult↗